Technical Field
The invention concerns an apparatus and a process for welding steel sheets for producing a rotor blade of a wind power installation. The invention also concerns a process and an apparatus for the manufacture of a rotor blade of a wind power installation. In addition the invention concerns a wind power installation and a rotor blade of a wind power installation. Furthermore the invention concerns an apparatus and a process for the hot forming of a steel sheet of a rotor blade of a wind power installation. In addition the invention concerns an apparatus and a process for cutting steel sheets to size for a rotor blade of a wind power installation.
Description of the Related Art
Wind power installations are known nowadays in particular in the form of so-called horizontal-axis wind power installations. In that case an aerodynamic rotor having at least one and usually three rotor blades rotates about a substantially horizontal axis. In that case the rotor blades are of an aerodynamic configuration and are moved by the wind so that said rotary movement takes place, which can then be converted into electrical energy by an electric generator.
Modern wind power installations have rotor blades which are of increasingly greater size and in particular greater length. In the meantime rotor blades of lengths of about 60 m, of a depth of up to over 8 m and a thickness of up to over 3 m are already known. A connecting flange of such a rotor blade for fixing a rotor hub also nowadays is already of a diameter of over 3.5 m. For rotor blades of such orders of magnitude it may be appropriate for them also to be at least portion-wise made from steel.
Steel production is known from many other technological areas such as for example ship building, but transfer to the manufacture of a rotor blade of a wind power installation is basically not possible because of the very special demands of rotor blade manufacture. In this connection mention is to be made in particular but not definitively of the fact that, in rotor blade manufacture, the aim in spite of everything is to implement a lightweight structure, insofar as that is at all possible when using steel. In addition it is to be noted that a rotor blade of a wind power installation is exposed to permanently changing loads. In that respect there is a change not only in loading amplitude but also loading direction and in particular upon rotary movement of the rotor the force of gravity can involve an ongoing change between tensile and compression loadings. In that respect a rotor blade is a long hollow body which must withstand even a constant and constantly changing flexural loading. In addition to ensuring appropriate stability however the rotor blade must be of an aerodynamic shape and as far as possible is to appropriately retain that shape. All those demands are so special that they require specific consideration dedicated thereto. In particular it is possible to have recourse to previous experience in steel constructions only to a severely limited extent.
For wind power installations, the ‘Smith-Putnam Wind Turbine’ is known from the 1940s, which used a steel rotor blade. Information about that ‘Smith-Putnam Wind Turbine’ is to be found on the English Wikipedia page (http://en.wikipedia.org/wiki/Smith-Putnam_wind_turbine). A rotor blade used there can also be found from the Internet, namely the Internet page http://www.situstudio.com/blog/2010/09/01/smith-putnam/.
As can be seen from the foregoing Internet blog the rotor blade of the Smith-Putnam Wind Turbine has been constructed with a rotor blade profile that is constant over the entire axis thereof. That naturally leads to simplifications in terms of production engineering in comparison with today's modern rotor blades which are of an axially continuously varying profile. In that respect the profile changes in the axial direction in size and also in its nature. In addition a rotor blade of a modern wind power installation of today is also twisted in the axial direction to take account of the different afflux flow directions which occur, due to the rotation of the rotor, at different spacings from the rotor hub. Added to that is the fact that particularly large rotor blades and in particular rotor blades of very great depth in the region near the hub must be of a multi-part structure for transport purposes.
The complexity of a modern rotor blade is therefore not to be compared to the rotor blade known from the Smith-Putnam Wind Turbine. Manufacturing a modern rotor blade or a portion of a modern rotor blade from steel thus requires a large number of individual considerations, approaches and solutions.
As general state of the art attention is to be directed to the documents DE 1 433 768 A, DE 1 180 709 A, DD 159 055 A1, DE 24 02 190A and WO 2010/100066 A2.